This invention relates to a method and apparatus for turning book or magazine pages placed on a document table.
In order to record information obtained from books or magazines on microfilms or other recording media, it is required to turn the book or magazine pages placed on a document table. It has been proposed to relieve the monotonous work by employing an automatic page turning apparatus. The conventional page turning apparatus employs a pressure differential to attract book or magazine pages. Although this type of automatic page turning apparatus has been widely accepted because of its capacity for producing a great attraction force, one serious difficulty occurs in that the pressure differential has an effect on the next page through a number of fine holes formed in the page to be turned so as to attract two or more pages at a time. For this reason, troublesome adjustments are required to obtain the proper attraction force necessary to turn only one page at a time. Another type of automatic page turning apparatus employs an electrostatic attraction force produced between an electrode and the book or document page to be turned to attract the page onto the electrode. However, such a conventional page turning apparatus sometimes fails to produce a sufficient attraction force particularly when the apparatus is used in an atmosphere having a high humidity.
Attempts have been made to overcome the difficulties associated with such conventional page turning apparatus. For example, Japanese Patent Kokai No. 57-102398 discloses an improved page turning apparatus which includes a suction pipe connected to an electric fan for producing a pressure differential used in attracting a book or document page. A strength gage, which is sensitive to the weight of the suction pipe, is used to determine whether one or more pages are attracted at a time. If the suction pipe attracts two or more pages, the attraction force is reduced by controlling the electric fan. Since the attraction force required to attract one page is different from one kind of paper to another, however, it is very difficult to produce an appropriate attraction force permitting only one book or document page to be attracted for various kinds of document paper. In addition, since the margin between an attraction force level required to attract one book or document page and the attraction force level required to attract two book or document pages is very small, the extent to which the attraction force can be increased is very small. Accordingly, it is very difficult to ensure reliable page turning operation.